Caretakers at Glasgow's primary schools are threatening to stop cleaning up spillages and picking up litter unless they are paid up to £1,000 extra every year. The workers, employed by Cordia - Scotland's biggest provider of facilities management services in local government - are also demanding back payments of the annual sum, which could cost the organisation more than £2million.

The caretakers say they are entitled to a 'Working Context and Demands Payment' for carrying out everyday jobs including weeding, litter picking, snow clearing, salt spreading, leaf raking, heavy lifting and mopping up spills - including vomit and other spilled bodily fluids.

Some workers are allocated points for duties which involve physical demand, working outdoors or dealing with unpleasant conditions such as cleaning up vomit or picking up dog dirt. If enough points are accumulated, a pensionable WCD payment is triggered which can be between £500 and £1,000.

However, primary school caretakers - who earn between £15,000 and £18,000 a year, are not allowed to claim the extra cash and The Evening Times reports that trade union Unison has begun balloting members for industrial action.

The ballot which, began this week, has also asked 90 workers whether they would stage walk-outs if Cordia did not agree to their demands. It is understood that a previous consultative ballot indicated almost 100% support for a work to rule, which would see caretakers refrain from carrying out some duties.

Unison is believed to want extra payments backdated to 2007, which could see around 250 janitors handed up to £8,000 each, costing Cordia more than £2million.

A senior source at Unison said: "We have exhausted the grievance procedures and they are basically saying they are not paying it so we have no option but to move to a ballot. Any action won't close schools but it will have a severe impact."

An email to members, which asks whether they will take strike action and 'action short of strike action' and seen by the Evening Times, states: "Unison is very clear that school janitors meet the scoring criteria to be awarded a WCD payment. There are five levels of annual WCD payment ranging from just over £500 to over £1000.

"The purpose of the action is to force Cordia into offering an acceptable WCD payment. Unison recommends that you vote yes to both questions. Your claim is modest and just."

A Cordia spokesman confirmed that the organisation employs 250 caretakers who work in primary schools, additional support for learning schools and nurseries - and said that 90 are Unison members. The Unison members are seeking additional payments for work that school caretakers have always carried out. "There has never been any extra payment for this kind of work and there's no justification for it now," they said.

Image (for illustration only) taken from Cordia website and not connected with this dispute in any way